<html>
<head>
<style>
.normal {font-weight:normal;}
.light {font-weight:lighter;}
.thick {font-weight:bold;}
.thicker {font-weight:900;}
</style>
</head>

<body>
<p class="normal">This is a paragraph.</p>
<p class="light">This is a paragraph.</p>
<p class="thick">This is a paragraph.</p>
<p class="thicker">This is a paragraph.</p>
</body>

</html>